There is a time compression multiplexing (TCM) system as a transmission system between transmission devices. The time compression multiplexing system is directed for realizing bidirectional transmission by performing time division on a pair of cables and repeating transmission and reception, and may be also called ping-pong transmission system. A technique for such a transmission system is described in Patent Literature 1.
With the bidirectional transmission device described in Patent Literature 1, when a transmission distance between a master machine and a slave machine is within a predetermined distance, a redundant period in a frame period is removed, thereby transmitting more data than in typical bidirectional transmission devices. Thereby, a performance of the entire transmission system can be enhanced.